1. What does it cost at double your current team?
Model it explicitly. Per-agent cloud pricing grows linearly with headcount; per-desk and self-hosted pricing does not. For a team likely to grow, this is often the deciding number and it is rarely calculated during evaluation.
2. Who is on call when it breaks?
Genuinely self-hosted means you are. Managed hosting of self-hosted software means somebody else is, while the installation remains yours. Pure cloud means the vendor is, and you have no visibility.
The middle option is underrated and is what most businesses actually want.
3. Where must the data live?
Some businesses have a real requirement — regulatory, contractual, or a large customer’s procurement questionnaire. Most do not, and should not pretend otherwise. But if you do, it eliminates most cloud options immediately.
4. Can you leave?
Ask for the export format and test it during the trial, on real data including attachments. The answer to this question is what you will care about in year three, and it is the one least often checked in year one.